Add an invoice item to a booking
- Add New - adds the invoice item regardless of whether it exists or not.
- Add New and Subtract - add an invoice item and at the same time add the same item with a negative value (to a different invoicee) making no nett change but effectively moving an item to a different invoicee
- Update or Add New - updates the invoice item if it exists, otherwise adds it as new.
- Update only - updates the invoice item if it exists but will not add as new.
Invoice items are matched on the description and optionally status if specified.
If the invoicee is not set to "ignore" it must also match.
For type = "Amount", "Percent of Charges" and "Percent of Price" the quantity, price and vat values are updated on all matched invoice items.
For the type = "Change Invoicee", only the invoicee is updated on matched items, the quantity, price and vat are unchanged.